1. Field of Invention
The present invention relates to an optical element inspection device and an optical element inspection method.
2. Description of Related Art
The related art includes a projector that includes a plurality of liquid crystal panels capable of modulating a plurality of color lights for each color light according to image information, a cross-dichroic prism for an optical element to synthesize the color lights modulated by each liquid crystal panel, and a projection lens to form a projected image by projecting the light beam synthesized by this cross-dichroic prism in an enlarging manner. Such a projector separates, for example, the light beam emitted from a light source into three color lights of RGB by a dichroic mirror, performs modulation according to image information for each color light by three liquid crystal panels, synthesizes the modulated light beam by a cross-dichroic prism, and projects a color image in an enlarging manner via the projection lens.
Such a cross-dichroic prism is a substantially cubic prism formed by affixing four rectangular prisms along each interface. In addition, a dielectric multi-layer film to reflect red light having a predetermined wavelength range is provided in a set of two reflective surfaces along the extending direction at four affixing surfaces, and a dielectric multi-layer film to reflect blue light having a wavelength range different from the above is provided in a set of the other two reflective surfaces along the extending direction. This means that four reflective surfaces are disposed in an X-shape inside the cross-dichroic prism.
Thus, in order to obtain a sharp projected image, each X-shaped reflective surface must reliably face the predetermined direction with respect to each liquid crystal panel. Therefore, in the related art, the cross-dichroic prism is fixed to a fixing member with high accuracy for unification based on the intersection formed by butting the contour dimension of the cross-dichroic prism against an end of each rectangular prism, i.e., the intersection of the reflective surface to reflect red light with the reflective surface to reflect blue light, and, accommodated in the projector together with this unit to specify the direction of each reflective surface.